Investigational Cancer Drug BSI-201 Showed Clinical Benefit in 62% of Patients with Triple-Negative Metastatic Breast Cancer and Significantly Prolonged Survival

June 3, 2009

PARIS and BRISBANE, California, June 3 /PRNewswire-FirstCall/ –

– Data Highlighted in Plenary Session of 2009 American Society of
Clinical Oncology Annual Meeting

Sanofi-aventis (EURONEXT: SAN and NYSE: SNY) and its fully owned
subsidiary, BiPar Sciences, today announced results from a randomized Phase 2
clinical trial of BSI-201, a poly ADP-ribose polymerase (PARP) inhibitor, in
combination with gemcitabine and carboplatin (GC) chemotherapy, in patients
with metastatic triple-negative breast cancer (TNBC). BSI-201 is a novel
investigational agent that acts by inhibiting PARP1, an enzyme that repairs
DNA damage.

In this study, 116 women with metastatic TNBC, defined as tumors lacking
expression of estrogen and progesterone receptors and without overexpression
of HER2, were randomly assigned to receive GC in combination with the
investigational agent BSI-201 or GC alone. Patients assigned to receive
chemotherapy without BSI-201 were allowed to receive BSI-201 at the time of
disease progression.

The primary study endpoint was the rate of clinical benefit, defined as
complete or partial response or stable disease of at least 6 months.
Secondary study endpoints included progression-free survival, overall
survival and safety.

Approximately 62 percent of patients receiving BSI-201 in combination
with GC showed clinical benefit, compared with 21 percent in the group
receiving chemotherapy alone (p= 0.0002). Tumor response (complete or partial
response) was observed in 48 percent of patients who received BSI-201
combined with chemotherapy, whereas patients receiving chemotherapy alone
showed a response rate of 16 percent. Women who received BSI-201 had a median
progression-free survival of 6.9 months and overall survival of 9.2 months
compared with 3.3 and 5.7 months, respectively, for women who received
chemotherapy alone. The hazard ratios for progression free survival and
overall survival were 0.342 (p< 0.0001) and 0.348 (p=0.0005), respectively.

The most common severe (grades 3 and 4) side effects included neutropenia
[25/57 in patients treated with GC and BSI-201; 31/59 patients treated with
GC alone], thrombocytopenia and anemia. No febrile neutropenia was observed
in patients receiving BSI-201 combined with chemotherapy. BSI-201 did not add
to the frequency or severity of adverse events associated with chemotherapy.

“The improvement in overall survival and progression free survival
together with the responses seen in this study are promising. We did not
observe added toxicities. BSI-201 may provide a potential new treatment
option for patients suffering from this disease,” said Joyce O’Shaughnessy,
M.D., co-director of the Breast Cancer Research Program at Baylor-Charles A.
Sammons Cancer Center and Texas Oncology in Dallas, Texas.

“These results represent an important development for a disease that
currently has no approved standard of treatment,” said Barry Sherman, M.D.,
BiPar’s Executive Vice President of Development. “Further study of BSI-201
will help us determine its full therapeutic potential in triple negative
breast cancer, as well as in other cancers”.

BiPar Sciences and sanofi-aventis expect to begin a Phase 3 trial with
BSI-201 in metastatic TNBC this summer.

About ASCO

ASCO is the world’s leading professional organization representing
physicians who care for people with cancer. Approximately 30,000 cancer
specialists from around the world are expected to gather at ASCO to discuss
the latest advances in cancer care, treatment, prevention and survivorship.
More than 4,000 abstracts have been accepted to the meeting, which will focus
on the theme of “Personalizing Cancer Care”, a practice focusing on caring
for the individual – not just treating the disease – through the entire
spectrum of care from prevention, diagnosis, and treatment to survivorship
and end of life care. For information on abstract embargo schedules and other
ASCO information and resources, visit http://www.asco.org/presscenter.

About BSI-201

Among other investigational PARP inhibitors in the industry, BSI-201 is
the furthest along in clinical development in metastatic TNBC. BSI-201 is
currently being evaluated for its potential to enhance the effect of
chemotherapy-induced DNA damage. The clinical development of BSI-201 is
supported by well documented safety profile based on studies of more than 200

About TNBC

When patients are diagnosed with breast cancer, their tumors are
routinely tested for the presence of estrogen and progesterone receptors and
for the over-expression of HER2. Commonly used breast cancer therapies target
these receptors; for example, tamoxifen for estrogen receptor and trastuzumab
(Herceptin(r)) for HER2. However, 15-20% of all breast cancers lack
over-expression of all three proteins, thus giving rise to the term “triple-
negative breast cancer” or “TNBC.”

TNBC can be an aggressive disease, with higher rates of metastases and
poorer survival rates than other breast cancer subtypes. No treatment has
been approved specifically for TNBC.

About BiPar Sciences

BiPar Sciences is a biopharmaceutical organization pioneering novel
tumor-selective therapies designed to address urgent unmet needs of cancer
patients. In addition to BSI-201, the company also has two additional
compounds in preclinical development. BiPar Sciences, located in Brisbane,
, is a fully-owned subsidiary of sanofi-aventis, Inc. For more
information, please visit http://www.biparsciences.com.

About sanofi-aventis

Sanofi-aventis is a leading global pharmaceutical company that discovers,
develops and distributes therapeutic solutions to help improve the lives of
patients. Sanofi-aventis is listed in Paris (EURONEXT: SAN) and in New York

Forward Looking Statements

This press release contains forward-looking statements as defined in the
Private Securities Litigation Reform Act of 1995, as amended. Forward-looking
statements are statements that are not historical facts. These statements
include financial projections and estimates and their underlying assumptions,
statements regarding plans, objectives, intentions and expectations with
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management believes that the expectations reflected in such forward-looking
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many of which are difficult to predict and generally beyond the control of
sanofi-aventis, that could cause actual results and developments to differ
materially from those expressed in, or implied or projected by, the
forward-looking information and statements. These risks and uncertainties
include those discussed or identified in the public filings with the SEC and
the AMF made by sanofi-aventis, including those listed under “Risk Factors”
and “Cautionary Statement Regarding Forward-Looking Statements” in
sanofi-aventis’ annual report on Form 20-F for the year ended December 31,
. Other than as required by applicable law, sanofi-aventis does not
undertake any obligation to update or revise any forward-looking information
or statements.

SOURCE Sanofi-aventis

Source: newswire

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